Which is the correct definition of tissues?
a.
the name for the developing organism from fertilization to about the eighth week of development.
b.
groups of similar cells that do a particular job.
c.
the basic units of heredity.
d.
threadlike structures that carry the codes for inherited traits.

when you breathe in, or inhale, your diaphragm contracts (tightens) and moves downward. this increases the space in your chest cavity, into which your lungs expand. the intercostal muscles between your ribs also enlarge the chest cavity. they contract to pull your rib cage both upward and outward when you inhale.